Stroke prevention guidelines highlight unique risks in women

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Women suffer more disabling strokes than men and need to become more aware of their unique risks, such as pregnancy complications and the use of oral contraceptives, according to a new set of recommendations released on Thursday by the American Heart Association and the American Stroke Association. The stroke prevention guidelines—the first to be released specifically for women—also point to risk factors more common in women like migraines with aura, type 2 diabetes, and obesity; such differences could point to why strokes are the third leading cause of death in women but only the fifth leading cause of death in men.

“These new guidelines are a call to action that doctors really need to be focusing more on women when it comes to stroke prevention,” said Dr. Shazam Hussain, head of the Stroke Section at the Cleveland Clinic., who was not involved with the guideline.

About 3 percent of Americans have lived through strokes, but as a result many suffer from permanent health problems such as impaired speech, memory loss, or paralysis. Women who develop dangerous hypertension during pregnancy, known as preeclampsia, have twice the risk of having a stroke later in life compared to those who had healthy pregnancies.

The new guidelines, published in the journal Stroke, directs doctors to consider preeclampsia to be a stroke risk factor akin to smoking, high cholesterol, and obesity because it’s likely to lead to hypertension years after the pregnancy.

“Internists should document this pregnancy complication as part of a woman’s medical record, yet many women report that their doctors never ask about their pregnancy history,” said the guideline lead author Dr. Cheryl Bushnell, a neurologist at Wake Forest Baptist Medical Center in Winston-Salem, NC.

Doctors should also screen for high blood pressure before prescribing oral contraceptives, the guideline states, since the estrogen they contain has been associated with a small increased risk of blood clots that could lead to a stroke if a clot blocks off the brain’s blood supply.

“Stroke risk is a discussion many of us already have with our patients before prescribing the pill,” especially among smokers over age 35 since they’re at greatest risk, said Dr. Errol Norwitz, chair of the obstetrics and gynecology at Tufts Medical Center. “I also check blood pressure after a woman starts the pill and will take her off if there’s an increase because of stroke concerns.”

Women who have migraines with visual auras -- which occur four times more frequently in women than in men -- also have an increased stroke risk and need to make concerted efforts to stop smoking, the guidelines recommend, because the two in combination can be particularly dangerous.

“Migraines, like preeclampsia, don’t likely cause strokes,” Norwitz said, “but could be a sign that there’s a predisposition for cardiovascular disease.”

Since strokes are rare in younger women, even a doubling in risk from preeclampsia or migraines means the likelihood remains pretty low. “A 40 year-old woman’s risk of having a stroke by age 45 may rise from 3 in 10,000 to 6 in 10,000 if she has a single risk factor,” Bushnell said. “But if you add in oral contraceptive use, a history of high blood pressure, and a diagnosis of type 2 diabetes—which all increase the risk of stroke—it becomes a substantial increased risk.”

In those cases, doctors need to urge patients to alter their lifestyle to decrease stroke risk by exercising, eating a diet based on fruits, vegetables, and whole grains, and losing excess weight, the guidelines recommend.

While that thrust is likely to be embraced by the medical community, some of the recommendations have raised eyebrows. The guideline authors recommended screening all women over age 75 for atrial fibrillation, an abnormal heart rhythm that’s linked to a higher stroke risk. But simple screening measures—listening to a pulse or performing an EKG—employed by primary care physicians often don’t detect the condition.

“It’s tricky and complicated to detect in those who aren’t having symptoms like heart palpitations,” Hussain said, “so I’m not really sure why it’s in there.”

The new guidelines advise gynecologists to treat pregnant women with hypertension with a calcium supplement if they don’t consumer much in their diet to lower preeclampsia risks, which Norwitz said is not based on solid evidence. He does, however, agree with other advice to treat them with a low-dose aspirin, which has been shown to lower risk -- although by just a modest 10 percent.

“The bottom line is nothing works particularly well to prevent preeclampsia,” Norwitz said, “but we’re increasingly recognizing that it has lifelong consequences and women can take steps to reduce their stroke risk later on.”